Wave movements in the sea and in large inland lakes constitute a potential source of energy that have been scarcely exploited so far. The same relates to underwater streams in the sea and to the wind above the sea. Although there have been a lot of different suggestions for generator aggregates utilizing these renewable energy sources for powering the generator, the amount of energy produced in this way is neglectable. The main reasons for that are economical. It is problematic to achieve aggregates of this kind that are economically competitive. Normally the power output from these aggregates is very small. Therefore, a large number of such aggregates are required to attain power of a significant level that can compete with conventional energy sources such as hydropower, nuclear power and aggregates powered by fossil fuels.
The challenge to achieve an economical competitive energy generating system based on these renewable energy sources is on one hand to provide efficient generator aggregates at low costs and on the other hand to provide an optimized system that can include a large number of such generator aggregates. The latter aspect is the crucial one for producing and supplying energy on a large commercial scale for the supply of the electric energy to an electric network. The present invention is focused on that aspect.
WO 03/058055 discloses a wave-power unit, including a linear generator. The unit is of a design such that it effectively generates electric energy at a comparatively low cost. This reference also discloses how a plurality of the units can be connected to a plurality of switchgears, each switchgear being connected to an intermediate station supplying the energy to a land based receiving station. Thus the reference discloses a system including many generator aggregates, the output from which is collected into a cable between the intermediate station and the land based receiving station. The disclosed system therefore is capable of providing electric energy at a power many times higher than that from a single generator aggregate. Typically a single aggregate deliver at a power level of 10 kW and the system in total will be able to supply energy at a power in the order of 300 kW.
However, this in most cases is far from sufficient to achieve a competitive energy supply system. Furthermore the disclosed system is limited to supplying to a particular location on land that can be connected to an electric network.
The object of the present invention is to provide a system for generating electric energy from renewable energy sources that is technically and commercially competitive for supplying the energy to a general electric network.
Another object is to provide a system allowing a high degree of flexibility regarding the supply to the network.